Mucidin-nonproducing mutants of oudemansiella mucida.

Mutants of Oudemansiella mucida, blocked in the biosynthesis of the antibiotic mucidin, were obtained at a 0.28% frequency after the application of N-methyl-N'-nitro-N-nitrosoguanidine (MNG) to basidiospores under conditions leading to 0.5--5.0% survival rates. Loss of antibiotic activity was in most isolates accompanied by a decrease in mycelium growth rate and a suppression of dikaryotizing and fructification ability. Recombination analysis of two stable mutants revealed that the block in mucidin synthesis is the result of mutation in the same chromosomal gene (muc). In contrast to the action of MNG, UV-irradiation leads neither to the loss of biosynthetic activity nor to any morphological change.